Thanks a lot Sunil, I will take a look at the changes and go from there. I really appreciate your help in this regard.

I have made the code such a way that it will populate the chart only once, this is easily modiifed in the code.
I have to create new chart every time user selects the dropdown box. The dropdown box gets set of data for chart to render that are stored in the DB. I guess I will know how the memory usage is when I create new chart every single time when I select a value from dropdown.